Explosively actuated tool



Nov. 21, 1967 R. TEMPLE ET AL EXPLOSIVELY ACTUATED TOOL 2 Sheets-Sheet 1 Filed Oct. 20, 1965 v INVENTORS. ROBE/P7 fP/VEJT E.

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Nov. 21, 1967 TEMPLE ET AL 3,353,445

EXPLOSIVELY ACTUATED TOOL Filed Oct. 20, 1965 2 Sheets-Sheet 2 INVENTORS. 9055/? T TEMPL E, Efi gf'fr E. TEMPLE C4 7" rap/v5 Y5.

United States Patent Ofiice 3,353,445 Patented Nov. 21, 1967 3,353,445 EXPLOSIVELY ACTUATED TOOL Robert Temple, Swissvale, and Ernest E. Temple, Murrysville, Pa., assignors to Mine Safety Appliances Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 20, 1965, Ser. No. 498,571 2 Claims. (Cl. 89-1) ABSTRACT OF THE DISCLOSURE A projectile-restraining disc member is rigidly mounted in a barrel behind a projectile. The disc member and projectile are provided with interengaging portions positively locking them together until the pressure of an exploded charge in the barrel rises to the point where one of the interengaging portions breaks off to permit the projectile to move forward.

Such tools are those in which a cutter, punch, bonder or other working projectile is caused to move forward at high velocity by detonating an explosive charge behind it. Usually, the explosive is in a blank cartridge. To give the force of the explosion opportunity to build up to a high pressure before the projectile moves forward, so that the projectile will travel at a higher velocity than otherwise would be the case, it is common practice to provide such tools with means for delaying movement of the projectile momentarily. Such means usually extend through the side of the barrel of the tool and therefore are objectionable for tools operating under water.

It is among the objects of this invention to provide an explosively actuated tool, in which initial movement of the projectile is restrained by means located entirely inside the tool barrel, and in which the restraining means holds the projectile in a predetermined position.

In accordance with this invention, the tool has a barrel in which a working projectile is slidably mounted. Separate projectile-restraining means are mounted in fixed position in the barrel behind the projectile. At the rear end of the barrel there are means for firing an explosive charge to create pressure that will drive the projectile forward away from its restraining means. The restraining means and the projectile are provided with interengaging portions to hold the projectile back until the explosive pressure behind it increases to the point where one of said interengaging portions will shear off to permit the projectile to be driven forward.

The invention is illustrated in the accompanying drawings, in which FIG. 1 is a plan view of out tool, partly broken away in section;

FIG. 2 is a longitudinal section of the tool taken on the line IIII of FIG. 1;

FIG. 3 is a cross section taken on the line IIIHI of FIG. 2;

FIG. 4 is a fragmentary longitudinal section showing the tool after the projectile has started to move forward;

FIG. 5 is a side view, partly in section, of a modification; and

FIG. 6 is a view of the front end of the modified cartridge holding member.

Referring to FIGS. 1, 2 and 3 of the drawings, the tool frame 1 may be of any conventional design provided with a barrel 2, in which there is a working projectile, which may be a cable cutting chisel 3 for example. In such a case, the front end of the frame is hook shape to form an open-sided recess 4 for receiving a chain link or cable that is to be cut by the chisel. The front end of the barrel opens into the back of the recess.

The rear portion of the chisel is cylindrical and engages the front of a cartridge-holding disc member 6 that is provided at its rear end with a peripheral flange 7 clamped against the rear end of the barrel by a cap 8 screwed onto the barrel. The disc is provided with a central opening, in which is mounted the rear end of an explosive cartridge 9 that extends forward into an axial chamber 10 in the chisel. The cartridge is held in place by means of a small breechblock 12 mounted in the cap and provided with a central opening for a firing pin 13 that is slidably mounted in an axial passage 14 in a rear extension of the cap. A hollow nut 15 is screwed onto the rear end of the cap, from which a retracting pin 16 attached to the firing pin projects. A ring 17, connected to the rear end of the retractor pin, permits the firing pin to be pulled back in the cap and released, whereupon a coil spring 18 around the firing pin will drive the pin forward to detonate the cartridge. The force of the explosion will cause the chisel to be driven ahead at high velocity across the cable recess and through any cable therein and against an anvil 19 of soft metal removably mounted in the front end of the frame.

It is a feature of this invention that for a moment after the cartridge is fired, the chisel is prevented by the cartridge-holding member from moving forward. This permits the pressure behind the chisel to build up to a higher value than would be the case if the chisel could start moving the moment the cartridge was discharged. Accordingly, the disc 6 and the adjoining end of the chisel are provided with interengaging portions, such as hooks, one of which breaks off when the pressure reaches a predetermined point. The hook 21 (FIG. 2) on the disc projects forward from it at one edge and preferably extends straight across the disc as shown in FIG. 3. The book may have a flat front surface in a plane perpendicular to the axis of the tool and connected by a rearwardly and outwardly extending fiat inclined surface to the main front surface of the disc. The adjoining rear face of the chisel is recessed to form its hook 22. This hook is shaped to nest with the hook on the disc so that the rear face of the chisel will substantially engage the front face of the disc. Since the chisel must be very hard in order to cut a metal cable or chain, it is preferred to make the disc of a softer metal so that it will be its hook 21 that will break or shear off when the force of the cartridge explosion increases to the desired point, as shown in FIG. 4, with the result that the chisel will be driven ahead at high velocity. The pressure at which this book will separate from the disc is determined by the area of the cross section of metal connecting the hook with the disc. The greater this area, the greater the pressure must be to break the hook away from the disc. The disc and hook thus form means for restraining forward movement of the chisel until high pressure has built up behind the chisel.

The hooks that connect the chisel and disc 6 together always hold them in the same positions relative to each other. Therefore, by shaping the cartridge holder so that it will fit in the barrel in only one position, the chisel always is positioned so that its cutting edge is transverse to any cable in the cutting recess 4. Accordingly, a segment of flange 7 is omitted to provide the periphery of the flange with a fiat area as shown at 25 in FIGS. 1 and 2, and the rear end of the barrel is provided beside that area with a rearward projection 26 having a flat area engaging the fiat area of the flange, as shown in FIGS. 2 and 3. The disc can be inserted in the barrel only when these two flat areas engage.

In the modification shown in FIGS. 5 and 6, no part of the chisel 30 or cartridge-holding disc member 31 is sheared off. Instead, those two elements are connected by a separate shear pin 32, which is sheared when pressure behind the chisel, due to firing the cartridge 33,

it reaches the desired point. For this purpose, the disc member has at one edge an integral lug 34 that overlaps the rear end portion of the chisel, the latter being provided with a notch 35 for receiving the lug. The lug and the portion of the chisel that it overlaps are provided with aligned radial openings 36 and 37 in which the shear pin 32 is fitted. The disc is provided with a peripheral flange 38 for clamping it in a tool frame barrel, and the flange has a flattened area 39 at one side of the disc so that the disc will fit in the barrel in only one position, as described in connection with the first embodiment.

It will be seen that with our invention the parts that restrain the chisel are completely housed in the barrel and also hold the chisel in correct position for cutting cables. No tools are required for assembling the chiselrestraining means. When the tool is fired, no part of the restraining means flys out of the tool.

According to the provisions of the patent statutes, we have explained the principle of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. An explosively actuated tool comprising a barrel, a working projectile slidably mounted therein provided in its rear end portion with an axial chamber to receive an explosive cartridge, a separate fiat disc member rigidly mounted in the barrel behind said projectile and covering the rear end of the projectile, said disc member being provided with a central opening therethrough aligned with said chamber for receiving and holding the rear end of said cartridge, and means at the rear end of the barrel for firing the cartridge to create pressure that will drive said projectile forward away from the disc member, said disc member and projectile being provided with integral hooks positively interlocked with each other to restrain the projectile while said pressure increases to a predetermined point, one of said hooks being adapted to shear off when said predetermined pressure is reached to permit the projectile to move forward, the hook on said disc member projecting forward from the edge thereof and extending less than 180 around the disc, and the rear face of said projectile in front of the disc member hook being recessed at the edge to form its hook.

2. An explosively actuated tool comprising a barrel, a working projectile slidably mounted therein provided in its rear end portion with an axial chamber to receive an explosive cartridge, a separate flat disc member rigidly mounted in the barrel behind said projectile and covering the rear end of the projectile, said disc member being provided with a central opening therethrough aligned with said chamber for receiving and holding the rear end of said cartridge, and means at the rear end of the barrel for firing the cartridge to create pressure that will drive said projectile forward away from the disc member, said disc member having at its edge a forwardly extending lu-g and the projectile being provided with a peripheral notch in its side receiving the lug between the projectile and the barrel, the lug and the portion of the projectile overlapped by it being provided with aligned radial openings, and a shear pin fitting in said radial openings.

References Cited UNITED STATES PATENTS 683,384 9/1901 Cole 10238 2,455,825 12/1948 Temple 891 X 2,755,550 7/1956 Benjamin 6()26.l X 3,176,615 4/1965 DeMatthew l02-38 X 3,237,335 3/1966 Kerr l02--4l X SAMUEL W. ENGLE, Primary Examiner. 

1. AN EXPLOSIVELY ACTUATED TOOL COMPRISING A BARREL, A WORKING PROJECTILE SLIDABLY MOUNTED THEREIN PROVIDED IN ITS REAR END PORTION WITH AN AXIAL CHAMBER TO RECEIVE AN EXPLOSIVE CARTRIDGE, A SEPARATE FLAT DISC MEMBER RIGIDLY MOUNTED IN THE BARREL BEHIND SAID PROJECTILE AND COVERING THE REAR END OF THE PROJECTILE, SAID DISC MEMBER BEING PROVIDED WITH A CENTRAL OPENING THERETHROUGH ALIGNED WITH SAID CHAMBER FOR RECEIVING AND HOLDING THE REAR END OF SAID CARTRIDGE, AND MEANS AT THE REAR END OF THE BARREL FOR FIRING THE CARTRIDGE TO CREATE PRESSURE THAT WILL DRIVE SAID PROJECTILE FORWARD AWAY FROM THE DISC MEMBER, SAID DISC MEMBER AND PROJECTILE BEING PROVIDED WITH INTEGRAL HOOKS POSITIVELY INTERLOCKED WITH EACH OTHER TO RESTRAIN THE PROJECTILE WHILE SAID PRESSURE INCREASES TO A PREDETERMINED POINT, ONE OF SAID HOOKS BEING ADAPTED TO SHEAR OFF WHEN SAID PREDETERMINED PRESSURE IS REACHED TO PERMIT THE PROJECTILE TO MOVE FORWARD, THE HOOK ON SAID DISC MEMBER PROJECTING FORWARD FROM THE EDGE THEREOF AND EXTENDING LESS THAN 180* AROUND THE DISC, AND THE REAR FACE OF SAID PROJECTILE IN FRONT OF THE DISC MEMBER HOOK BEING RECESSED AT THE EDGE TO FORM ITS HOOK. 